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Single crystals of hydrogen bonded 4-methoxyanilinium perchlorate (4MAPC) have been grown and the corresponding structure has been confirmed by Single crystal XRD analysis. The charge transfer on the nitrogen site of 4-methoxyaniline has been confirmed from elongated carbon and nitrogen bond distances. The Quantum chemical calculations of 4-methoxyanilinium perchlorate have been studied at HF and DFT methods with 6-311++G(d,p) level of theory to get the optimized geometry, FT-IR/FT-Raman spectra, charge distributions and the microscopic NLO efficiency of the title compound. The HOMO-LUMO analysis indicates that the electron delocalization and the energy gap between the HOMO-LUMO of the 4MAPC indicates the charge transfer within the molecule. The energy gap values between the molecular orbitals are 4.7358 eV (DFT)/6.8044(HF) eV, which makes the compound more reactive. The Population analysis has been studied and discussed. The Hirshfeld surface analysis suggests that the most significant contribution to the crystal packing is by O...H contacts (29%). The microscopic NLO parameters of 4MAPC have been calculated and the relative second order hyperpolarizability (γ) of the compound has found to be 47 times greater than that of standard Urea.. [ABSTRACT FROM AUTHOR]

The structural evolution, electronic property and spectral analysis of YGenq (n = 4–20, q = 0, −1) has been examined under the framework of density functional theory combined with the Artificial Bees Colony and the Saunders 'Kick' algorithm. The global minimum structure of the YGen- cluster is recognised by contrasting the simulated and measured photoelectron spectra (PES). Average binding energies, second difference energies, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps are shown as size change and display abnormal stability at n = 16. Natural population analysis (NPA) shows the charge transfer from Ge to Y atom is 4.62 e in YGe16-, forming ionic bonds. HOMO–LUMO orbitals are mainly composed of Ge atoms. Electron localisation function (ELF) reveals the electrostatic force between Y and Ge atoms and the covalent interaction between each two Ge atoms, which is in accordance with the bond analysis. The current work shows that YGe16- is viewed as a promising building block for rare earth-doped semiconductor materials. [ABSTRACT FROM AUTHOR]

The industry has long sought ever more efficient materials, allowing it to meet market demand. For this purpose, doping remains a good choice for improving the properties of a material. The structural, electronic, optical properties of the G a S e 1 − x S x (x = 0, 0.25, 0.5 and 1) compounds are studied using the pseudopotential method of first principles in the Density Functional Theory using CASTEP code. The calculated results show that the lattice constants of ε-GaSe decrease as function of the impurity concentration increases. Also, the increase of doping by the sulphur leads to a decrease of D G a − X and an increase of D G a − G a . The values of the gap energy are increased with the increase in sulphur content. For optical calculations the results show the appearance of an absorption peak in all G a S e 1 − x S x (x = 0, 0.25, 0.5 and 1) structures, with different intensities and a shift of the band to lower wavelengths when the doping content by the sulphur is increased. The insertion of the sulphur atom reduces the refractive index of ε-GaSe, and increases its birefringence which is important for non-linear optics applications. Raman lines move to higher frequencies with increasing sulphur content indicating a change in the crystal structure of ε-GaSe. [ABSTRACT FROM AUTHOR]

The stable configurations, electronic structures and catalytic activities of single-atom metal catalyst anchored silicon-doped graphene sheets (3Si-graphene-M, M = Ni and Pd) are investigated by using density functional theory calculations. Firstly, the adsorption stability and electronic property of different gas reactants (O2, CO, 2CO, CO/O2) on 3Si-graphene-M substrates are comparably analysed. It is found that the coadsorption of O2/CO or 2CO molecules is more stable than that of the isolated O2 or CO molecule. Meanwhile, the adsorbed species on 3Si-graphene-Ni sheet are more stable than those on the 3Si-graphene-Pd sheet. Secondly, the possible CO oxidation reactions on the 3Si-graphene-M are investigated through Eley–Rideal (ER), Langmuir–Hinshelwood (LH) and new termolecular Eley–Rideal (TER) mechanisms. Compared with the LH and TER mechanisms, the interaction between 2CO and O2 molecules (O2 + CO → CO3, CO3 + CO → 2CO2) through ER reactions (< 0.2 eV) are an energetically more favourable. These results provide important reference for understanding the catalytic mechanism for CO oxidation on graphene-based catalyst. [ABSTRACT FROM AUTHOR]

The geometries, electrical characters and reaction paths from Fe(CO)5molecule to small Fe clusters were investigated by using all-electron density functional theory. The results show that in the decomposition process of pentacarbonyl-iron, Fe(CO)5molecule prefers to remove a carbon monoxide and adsorb another Fe(CO)5molecule to produce nonacarbonyldiiron Fe2(CO)9then Fe2(CO)9gradually removes carbon monoxide to produce small Fe clusters. As It can be seen from the highest occupied molecule orbital–lowest unoccupied molecule orbital gap curves, the Fe(CO)n=3, and 5and Fe2(CO)n=3, 7 and 9intermediates have higher chemical stability than their neighbors. The local magnetic moment of the carbon monoxide is aligning anti-ferromagnetic. The effect of external magnetic field to the initial decomposition products of Fe(CO)5can be ignored. [ABSTRACT FROM AUTHOR]

A systematic study of the X2Aun(X = La, Y, Sc;n= 1–9) clusters are performed by using the density functional theory at TPSS level. The structures, stabilities, electronic, and magnetic properties are investigated in comparison with pure gold clusters. The results show that the transition points of the doped clusters from two-dimensional to three-dimensional structure are obviously earlier than gold clusters. The impurity X atoms tend to occupy the most highly coordinated position and form the largest probable number of bonds with gold atoms. In addition, the impurity atoms can strongly enhance the stabilities of gold clusters. It indicates that the impurity atoms dramatically affect the geometries and stabilities of the Aunclusters. The highest occupied molecular orbital–lowest occupied molecular orbital gap, vertical ionisation potential, and chemical hardness show that the X2Au6clusters have higher stabilities than the others. In La2Au1–9, Y2Au1–7, and Sc2Au1–4clusters, the charges transfer from X atoms to the Aunframes. The total magnetic moments of X2Aunclusters exist distinctly odd–even alternation behaviours except for La2Au4and Sc2Au4clusters. [ABSTRACT FROM AUTHOR]

In this paper, we study the effect of uniaxial and biaxial strain on the structural and electronic properties of MoSmonolayers by first-principle calculations based on density functional theory. Our calculations show that the bond length between Mo and S atomsdepends linearly on the strain. At the equilibrium state, MoShas a direct band gap of 1.72 eV opening at the K-point. However, an indirect–direct band gap transition has been found in MoSmonolayer when the strain is introduced. MoSbecomes a semiconductor with an indirect band gap when the uniaxial strainor the biaxial strain. Under biaxial strain, a metal–semiconductor transition occurs atof elongation. The indirect character and phase transition will largely constrain application of MoSmonolayer to electronic and optical devices. [ABSTRACT FROM PUBLISHER]

Density functional theory has been applied to study the geometric structures, relative stabilities, and electronic properties of cationic [AunRb]+and Aun+1+(n= 1–10) clusters. For the lowest energy structures of [AunRb]+clusters, the planar to three-dimensional transformation is found to occur at cluster sizen= 4 and the Rb atoms prefer being located at the most highly coordinated position. The trends of the averaged atomic binding energies, fragmentation energies, second-order difference of energies, and energy gaps show pronounced even–odd alternations. It indicated that the clusters containing odd number of atoms maintain greater stability than the clusters in the vicinity. In particular, the [Au6Rb]+clusters are the most stable isomer for [AunRb]+clusters in the region ofn= 1–10. The charges in [AunRb]+clusters transfer from the Rb atoms to Aunhost. Density of states revealed that the Au-5d, Au-5p, and Rb-4p orbitals hardly participated in bonding. In addition, it is found that the most favourable channel of the [AunRb]+clusters is Rb+cation ejection. The electronic localisation function (ELF) analysis of the [AunRb]+clusters shown that strong interactions are not revealed in this study. [ABSTRACT FROM AUTHOR]

Ab initiocalculations (B3LYP and PBE-D3) of the structures, stabilities, vibrational, electronic and hydrogen adsorption behaviour of (MgO)nclusters are performed using 6-311+ + G(d,p) basis set. The planar (MgO)nclusters are found to be global minima forn ≤ 3 and local minima forn = 4 and 5. In addition, we have also analysed global minimum structures of (MgO)4and (MgO)5. The binding energies suggest that their stabilities increase successively. Vibrational frequencies and IR intensities further support the enhanced stability with an increase in the size of (MgO)nclusters. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) surfaces are used to explain and discuss the electronic properties. Finally, we have demonstrated hydrogen storage capacity of (MgO)nclusters, considering hydrogen adsorption on planar as well as global minimum (MgO)4and (MgO)5clusters. We have noticed that four and five H2molecules can be easily adsorbed by (MgO)4and (MgO)5clusters having adsorption energy of 0.13–0.14 eV with mass ratio of 4.76%. Thus, the present study is expected to motivate further the applications of small clusters for efficient hydrogen energy storage. [ABSTRACT FROM PUBLISHER]

Structural and electronic properties of Fe2P4O12have been investigated using first-principles calculation technique. The results indicated that the Fe2P4O12structure is monoclinic ofC2/cwith lattice parameters ofa= 12.228 Å,b= 8.530 Å,c= 9.835 Å and β = 118.67°. Two nonequivalent octahedral FeO6from the calculation have an average Fe−O distance of 2.143 Å. Both FeO6are dominated by covalent interactions assigned to Fe3dand O2pat the valent electronic states. The DOS calculation gives well explanation on its half-metallic ferromagnetic property. These results are in very good agreement with the previous experimental reports. [ABSTRACT FROM AUTHOR]

In this work, a density functional survey on manganese oxyfluoride (MnOxFy) species forx+y= 1–4 is performed, in which an Mn atom interacts simultaneously with O as well as F atoms. The stabilities of all these species are established against dissociation to manganese oxides as well as fluorides and their relative stabilities are also discussed. It is revealed that the most favourable oxidation state of Mn is +4 in its oxyfluorides, same as in fluorides. For the first time, the superhalogen properties of MnOF3, MnO3F and MnO2F2species are introduced on the basis of their high electron affinities as compared to halogens. The interaction of MnO2F2superhalogen with an alkali metal (K) is considered via F atoms as well as O atoms which is similar to that in KF and leads to the formation of stable KMnO2F2complex. Thus, this study is expected to motivate theorist to design a new series of superhalogen species using transition metals with mixed F and O ligands, as well as experimentalists to synthesise such novel complex compounds. [ABSTRACT FROM AUTHOR]

The magneto-electronic properties of quasi-one-dimensional zigzag graphene nanoribbons are investigated by using the Peierls tight-binding model. Quasi-Landau levels (QLLs), dispersionless Landau subbands within a certain region of-space, are resulted from the competition between magnetic and quantum confinement effects. In bilayer system, the interlayer interactions lead to two groups of QLLs, one occurring at the Fermi level and the other one occurring at higher energies. Transverse electric fields are able to distort energy spectrum, tilt two groups of QLLs, and cause semiconductor-metal transition. From the perspective of wave functions, the distribution of electrons is explored, and the evolution of Landau states under the influence of electric fields is clearly discussed. More interestingly, the band mixing phenomena exhibited in the energy spectrum are related to the state mixing, which can be seen by the wave functions. The density of states, which could be verified through surface inspections and optical experiments, such as scanning tunneling spectroscopy and absorption spectroscopy, is provided at last. [ABSTRACT FROM AUTHOR]

In the present paper, we have used density functional theory to study electronic properties of bilayer graphene and graphyne doped with B and N impurities in the presence of electric field. It has been demonstrated that a band gap is opened in the band structures of the bilayer graphene and graphyne by B and N doping. We have also investigated influence of electric field on the electronic properties of BN-doped bilayer graphene and graphyne. It is found that the band gaps induced by B and N impurities are increased by applying electric field. Our results reveal that doping with B and N, and applying electric field are an effective method to open and control a band gap which is useful to design carbon-based next-generation electronic devices. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of silver-doped gold clusters AunAgv (2 ≤ n ≤ 10; v = 0, ±1) have been systematically investigated using density functional theory. The results show that the ground state optimal structures of the cationic and neutral clusters are found to be planar up to n = 3 and 9, respectively. However, for the anionic clusters, no three-dimensional lowest-energy structures are obtained according to DFT calculations. The calculated binding energy and dissociation energy as a function of cluster size exhibit odd-even alternations. The natural population analysis indicates that in AunAgv clusters charges transfer from the Ag atom to the Au frames. The trends for the vertical detachment energies, adiabatic electron affinities, adiabatic ionization potentials, and chemical hardness of AunAgv clusters, as the cluster size increases, are studied in detail and compared with the available experimental data. [ABSTRACT FROM AUTHOR]

The geometric structures, relative stabilities, and electronic properties of a series of tetra-aluminum oxide clusters, [image omitted] ( [image omitted], [image omitted]), were systematically investigated using density functional theory calculations at the B3LYP level. The optimized geometries reveal a structural transition from a two-dimensional to a three-dimensional structure for n ≤5 for the neutral species, but the three-dimensional structures are preferable for all negative clusters with the exception of [image omitted]. The dissociation energy, the second difference energy and the highest occupied-lowest unoccupied molecular orbital gaps as a function of the cluster size exhibit a significant even-odd alternation phenomenon. It is found that the neutral [image omitted] cluster is relatively stable and exhibits strong chemical stability. Furthermore, the calculated (vertical and adiabatic) electron detachment energies are also compared with previous experimental data obtained from photoelectron spectra. [ABSTRACT FROM AUTHOR]

Abstract: The dinucleic octaethylporphyrin (OEP) derivatives described as OEP-(p-Phen) n -OEP (n=1–4) were synthesized, in each of which the porphyrin ring is spaced with p-phenylene group. Their electronic properties were studied, as compared with those of the corresponding dihexylbithiophene (DHBTh) derivatives with head-to-head (HH) and tail-to-tail (TT) orientations. It proves that OEP-(p-Phen) n -OEP possesses an in-between feature of OEP-(HH-DHBTh) n -OEP and OEP-(TT-DHBTh) n -OEP in electronic properties. [Copyright &y& Elsevier]

Water-soluble porphyrin-porphyrin and porphyrin-CdSe nanoparticle monolayer films were self-assembled on different substrates. The influence of substrates, types of films, and heat treatment temperature on fluorescence of different kinds of porphyrin films was investigated. The SEM images showed the formation of monolayer films on porous alumina foil. The films assembled on porous alumina foil possessed higher fluorescence intensity and thermal stability. The result of conductance measurement indicated that the interaction of trimethylamidophenylporphyrin iodide (TAPPI) molecules with hydroxyl groups on porous alumina foil was weakened after CdSe nanoparticles assembled with TAPPI. [ABSTRACT FROM AUTHOR]

Abstract: A new trimeric octaethylporphyrin (OEP) derivative was synthesized, in which each porphyrin ring is connected with diacetylene linkage. Its electronic absorption spectrum was examined, proving that the diacetylene linkage induces splitting of Soret band of OEP into two main bands with clear maxima at 429 and 481nm and more bathochromic shift of Q band to appear in such a longer wavelength region at λmax=670nm in chloroform, in contrast with that of the corresponding vinylene-group connected OEP trimer. It was shown that the spectrum of the present diacetylene-group connected OEP derivative drastically changed in pyridine, suggesting a coordination of pyridine molecule as the fifth ligand onto Ni(II) metal of the central ring. Furthermore, Vilsmeier formylation, a typical electrophilic substitution on the aromatic compounds, was examined for further oligomerization of OEP, proving that it takes place at the central ring exclusively. [Copyright &y& Elsevier]